hkdf.c File Reference

#include "precomp.h"

Include dependency graph for hkdf.c:

Go to the source code of this file.

Functions
SYMCRYPT_ERROR SYMCRYPT_CALL	SymCryptHkdfExpandKey (_Out_ PSYMCRYPT_HKDF_EXPANDED_KEY pExpandedKey, _In_ PCSYMCRYPT_MAC macAlgorithm, _In_reads_(cbIkm) PCBYTE pbIkm, SIZE_T cbIkm, _In_reads_opt_(cbSalt) PCBYTE pbSalt, SIZE_T cbSalt)
SYMCRYPT_ERROR SYMCRYPT_CALL	SymCryptHkdfExtractPrk (_In_ PCSYMCRYPT_MAC macAlgorithm, _In_reads_(cbIkm) PCBYTE pbIkm, SIZE_T cbIkm, _In_reads_opt_(cbSalt) PCBYTE pbSalt, SIZE_T cbSalt, _Out_writes_(cbPrk) PBYTE pbPrk, SIZE_T cbPrk)
SYMCRYPT_ERROR SYMCRYPT_CALL	SymCryptHkdfPrkExpandKey (_Out_ PSYMCRYPT_HKDF_EXPANDED_KEY pExpandedKey, _In_ PCSYMCRYPT_MAC macAlgorithm, _In_reads_(cbPrk) PCBYTE pbPrk, SIZE_T cbPrk)
SYMCRYPT_ERROR SYMCRYPT_CALL	SymCryptHkdfDerive (_In_ PCSYMCRYPT_HKDF_EXPANDED_KEY pExpandedKey, _In_reads_opt_(cbInfo) PCBYTE pbInfo, SIZE_T cbInfo, _Out_writes_(cbResult) PBYTE pbResult, SIZE_T cbResult)
SYMCRYPT_ERROR SYMCRYPT_CALL	SymCryptHkdf (PCSYMCRYPT_MAC macAlgorithm, _In_reads_(cbIkm) PCBYTE pbIkm, SIZE_T cbIkm, _In_reads_opt_(cbSalt) PCBYTE pbSalt, SIZE_T cbSalt, _In_reads_opt_(cbInfo) PCBYTE pbInfo, SIZE_T cbInfo, _Out_writes_(cbResult) PBYTE pbResult, SIZE_T cbResult)

Function Documentation

SymCryptHkdf()

SYMCRYPT_ERROR SYMCRYPT_CALL SymCryptHkdf	(	PCSYMCRYPT_MAC	macAlgorithm,
		_In_reads_(cbIkm) PCBYTE	pbIkm,
		SIZE_T	cbIkm,
		_In_reads_opt_(cbSalt) PCBYTE	pbSalt,
		SIZE_T	cbSalt,
		_In_reads_opt_(cbInfo) PCBYTE	pbInfo,
		SIZE_T	cbInfo,
		_Out_writes_(cbResult) PBYTE	pbResult,
		SIZE_T	cbResult
	)

Definition at line 186 of file hkdf.c.

{
    SYMCRYPT_ERROR scError = SYMCRYPT_NO_ERROR;
    SYMCRYPT_HKDF_EXPANDED_KEY key;
 
    // Create the expanded key
    scError = SymCryptHkdfExpandKey(
        &key,
        macAlgorithm,
        pbIkm,
        cbIkm,
        pbSalt,
        cbSalt );
    if (scError != SYMCRYPT_NO_ERROR)
    {
        goto cleanup;
    }
 
    // Derive the key
    scError = SymCryptHkdfDerive(
        &key,
        pbInfo,
        cbInfo,
        pbResult,
        cbResult );
    if (scError != SYMCRYPT_NO_ERROR)
    {
        goto cleanup;
    }
 
cleanup:
    SymCryptWipeKnownSize(&key, sizeof(key));
 
    return scError;
}

SymCryptHkdfDerive()

SYMCRYPT_ERROR SYMCRYPT_CALL SymCryptHkdfDerive	(	_In_ PCSYMCRYPT_HKDF_EXPANDED_KEY	pExpandedKey,
		_In_reads_opt_(cbInfo) PCBYTE	pbInfo,
		SIZE_T	cbInfo,
		_Out_writes_(cbResult) PBYTE	pbResult,
		SIZE_T	cbResult
	)

Definition at line 106 of file hkdf.c.

{
 
    SYMCRYPT_ERROR scError = SYMCRYPT_NO_ERROR;
 
    SYMCRYPT_MAC_STATE state;
 
    PCSYMCRYPT_MAC pMacAlgorithm = pExpandedKey->macAlg;
 
    SYMCRYPT_ALIGN BYTE    rbPartialResult[SYMCRYPT_MAC_MAX_RESULT_SIZE];
                   BYTE *  pbCurr = pbResult;
 
    SIZE_T  cbMacResultSize = pMacAlgorithm->resultSize;
 
    BYTE cntr = 0x01;
 
    // Check that cbResult <= 255*HashLen
    if (cbResult > 0xff * cbMacResultSize)
    {
        scError = SYMCRYPT_WRONG_DATA_SIZE;
        goto cleanup;
    }
 
    // In the first iteration T(0) is the empty string
    // Calculate T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
    pMacAlgorithm->initFunc( &state, pExpandedKey );
    pMacAlgorithm->appendFunc( &state, pbInfo, cbInfo );
    pMacAlgorithm->appendFunc( &state, &cntr, sizeof(cntr) );
    pMacAlgorithm->resultFunc( &state, rbPartialResult );
 
    // Store the result in the output buffer
    memcpy(pbCurr, rbPartialResult, SYMCRYPT_MIN(cbResult, cbMacResultSize));
    if (cbResult <= cbMacResultSize)
    {
        goto cleanup;
    }
 
    // Update counters
    cntr++;
    pbCurr += cbMacResultSize;
    cbResult -= cbMacResultSize;
 
    while( cbResult > 0 )
    {
        // Calculate T(i) = HMAC-Hash(PRK, T(i-1) | info | 0xi)
        pMacAlgorithm->initFunc( &state, pExpandedKey );
        pMacAlgorithm->appendFunc( &state, rbPartialResult, cbMacResultSize );
        pMacAlgorithm->appendFunc( &state, pbInfo, cbInfo );
        pMacAlgorithm->appendFunc( &state, &cntr, sizeof(cntr) );
        pMacAlgorithm->resultFunc( &state, rbPartialResult );
 
        // Store the result in the output buffer
        memcpy(pbCurr, rbPartialResult, SYMCRYPT_MIN(cbResult, cbMacResultSize));
        if (cbResult <= cbMacResultSize)
        {
            goto cleanup;
        }
 
        // Update counters
        cntr++;
        pbCurr += cbMacResultSize;
        cbResult -= cbMacResultSize;
    }
 
cleanup:
    SymCryptWipeKnownSize(&rbPartialResult[0], sizeof(rbPartialResult));
 
    return scError;
}

Referenced by SymCrypt802_11SaeCustomCreatePTGeneric(), and SymCryptHkdf().

SymCryptHkdfExpandKey()

SYMCRYPT_ERROR SYMCRYPT_CALL SymCryptHkdfExpandKey	(	_Out_ PSYMCRYPT_HKDF_EXPANDED_KEY	pExpandedKey,
		_In_ PCSYMCRYPT_MAC	macAlgorithm,
		_In_reads_(cbIkm) PCBYTE	pbIkm,
		SIZE_T	cbIkm,
		_In_reads_opt_(cbSalt) PCBYTE	pbSalt,
		SIZE_T	cbSalt
	)

Definition at line 18 of file hkdf.c.

{
    SYMCRYPT_ERROR scError = SYMCRYPT_NO_ERROR;
 
    SYMCRYPT_ALIGN BYTE rbPrk[SYMCRYPT_MAC_MAX_RESULT_SIZE] = { 0 };
 
    SYMCRYPT_ASSERT( macAlgorithm->expandedKeySize <= sizeof( pExpandedKey->macKey ) );
 
    scError = SymCryptHkdfExtractPrk( macAlgorithm, pbIkm, cbIkm, pbSalt, cbSalt, rbPrk, macAlgorithm->resultSize );
    if (scError != SYMCRYPT_NO_ERROR)
    {
        goto cleanup;
    }
 
    scError = SymCryptHkdfPrkExpandKey( pExpandedKey, macAlgorithm, rbPrk, macAlgorithm->resultSize );
    if (scError != SYMCRYPT_NO_ERROR)
    {
        goto cleanup;
    }
 
cleanup:
    SymCryptWipeKnownSize(&rbPrk[0], sizeof(rbPrk));
 
    return scError;
}

Referenced by SymCrypt802_11SaeCustomCreatePTGeneric(), and SymCryptHkdf().

SymCryptHkdfExtractPrk()

SYMCRYPT_ERROR SYMCRYPT_CALL SymCryptHkdfExtractPrk	(	_In_ PCSYMCRYPT_MAC	macAlgorithm,
		_In_reads_(cbIkm) PCBYTE	pbIkm,
		SIZE_T	cbIkm,
		_In_reads_opt_(cbSalt) PCBYTE	pbSalt,
		SIZE_T	cbSalt,
		_Out_writes_(cbPrk) PBYTE	pbPrk,
		SIZE_T	cbPrk
	)

Definition at line 52 of file hkdf.c.

{
    SYMCRYPT_ERROR scError = SYMCRYPT_NO_ERROR;
 
    SYMCRYPT_MAC_STATE state;
    SYMCRYPT_MAC_EXPANDED_KEY key;
 
    // Ensure that pbPrk is the correct size
    if (cbPrk != macAlgorithm->resultSize)
    {
        scError = SYMCRYPT_INVALID_ARGUMENT;
        goto cleanup;
    }
 
    // Calculation of PRK = HMAC-Hash(salt, IKM)
    scError = macAlgorithm->expandKeyFunc( &key, pbSalt, cbSalt );
    if (scError != SYMCRYPT_NO_ERROR)
    {
        goto cleanup;
    }
 
    macAlgorithm->initFunc( &state, &key );
    macAlgorithm->appendFunc( &state, pbIkm, cbIkm );
    macAlgorithm->resultFunc( &state, pbPrk );
 
cleanup:
    SymCryptWipeKnownSize(&key, sizeof(key));
 
    return scError;
}

Referenced by SymCryptHkdfExpandKey().

SymCryptHkdfPrkExpandKey()

SYMCRYPT_ERROR SYMCRYPT_CALL SymCryptHkdfPrkExpandKey	(	_Out_ PSYMCRYPT_HKDF_EXPANDED_KEY	pExpandedKey,
		_In_ PCSYMCRYPT_MAC	macAlgorithm,
		_In_reads_(cbPrk) PCBYTE	pbPrk,
		SIZE_T	cbPrk
	)

Definition at line 92 of file hkdf.c.

{
    SYMCRYPT_ASSERT( macAlgorithm->expandedKeySize <= sizeof( pExpandedKey->macKey ) );
 
    pExpandedKey->macAlg = macAlgorithm;
    return macAlgorithm->expandKeyFunc( &pExpandedKey->macKey, pbPrk, cbPrk );
}

Referenced by SymCryptHkdfExpandKey().